Pressure responsive switch for indicators



June 13, 1950 K. L; M GUIRE PRESSURE RESPONSIVE SWITCH FOR INDICATORSFiled Aug. 25, 1947 f W 8 W4 G w Y 3 3 R G E F m Q Wm W m 6 T 2 L J A HM T E N N m 7 0w 2 B 0 3 8 n z 6%, a r I A g 4 w H \Y. 7 Z 407 Ti ,5743u/flr3u/3 G H F Patented June 13, 1950 UNITED STATES PATENT OFFICEPRESSURERESPONSIVE SWITCH FOR INDICATORS Kenneth L. McGuire,. Beloit,Wis., assignor to. Fairbanks, Morse & 00., Chicago, 111., a corno rationof Illinois Application August 25, 1947, Serial No. 770,475

7 Claims. (Cl. 200-83) This invention is directed to the general class;

combustion space, usually include apressurere sponsive pick up unitwhich embodies a diaphragm member exposed at one side to thepressurebeing studied and exposed at its opposite side to the influenceof a controllable test pressure. The flexing of such a diaphragm undercertain differential pressure conditions is utilized to close anelectrical circuit associated with a suitable recording or indicatinginstrument. Most, if not all, of the pressure units now in; use areconstructed with the diaphragm member securely clamped at itsperiphery'whereby to effect a positive separation between. the diaphragmchamber spaces: exposed to the test pressure and the'pressure beinginvestigated. ihe fixed type of diaphragm is, therefore, subjected todestructive fatigue stresses which will eventually develop intopermanent deformation of the diaphragm, cause errors in the fidelity ofthe pressure response, retard the desired rapidity of response, and inother respects cause the introduction of errors materially affecting thetrue pressure conditions.

Accordingly, it isalso an important object of the present invention todesign and construct a pressure responsive ::unit whichwill'notsbeaffected bythe above noted objections almost invariably foundin the devices currently in use.

It is also an object to-simpliiy' the-construction of a pressureresponsive unit. such that the pressurized diaphragm may be entirelyunrestricted and .freely movable over its full area, securely retainedin a closely defined chamber for rapid response to the net efiect ofopposed pressure from a test source and. a source under investigation,.and required to have a minimum of movement'into or out of a position ofcontact with an electrode element of the associated electrical indicatorcircuit.

Other objects andtadvantagesof the present invention will be more fullypointed outsin connec- 2 tion with the detailed description of apreferred embodiment hereof as is disclosed in the accompanying drawing.

In the drawing:

Fig. 1 isa diagrammatic layout of a pressure indicator system serving toshow the operative relation of the pressure responsive unit in con--nection' with an internal combustion engine, the latter being shown inschematicand partly sectioned' elevation;

Fig. 2 is an enlarged longitudinal sectional elevational view of theimproved unit forming the subject of the invention; and

Fig. 3 is a greatly enlarged and fragmentaryportion, in section, of theimproved unit in which certain details are shown to better advantage.

Inthe view of Fig. 1, the-engine under test isrepresented bythe singlecylinder ill, piston 1.1 and crankshaft l2 to which the piston is operativel-y connected by the connecting rod 13. The cylinder has the usualhead member 14 which cooperates with the cylinder and piston to define acombustion space I5. My improved unit i6 is suitably mounted in the head14 for communication with the space t5 whereby pressure conditionstherein may be investigated. The unit ii is associated with an. engineindicator instrument, shown onlygenerally at I'Lthrough the electricalline ['8 and the pressure line 1.9, each of these lines l8 and i9 havinga suitable connection with sources (not shown) of electrical energy andfluid under pressure respectively. It is, of course, understood that thecylinder I0 is grounded to complete the circuit through line l8 and unit16.

Briefly considered, the instrument I! carries means for recording thedesired cyclic pressure events in space l5upona drum means 20 which isrotated in timed relation with crank movement through the clutchconnected. shaft 2|. Thus a recordoi the combustion pressure conditionsmay be recorded on drum 20 for any position of the piston II- asdetermined by the angular position of the crankshaft l2. The instrument[1, of course, must be adjusted to provide a known pressure in line I .9and when ever-the pressure in thespace 15 exceeds. this test pressure,an electrical circuit through line IE will be completed for energizingthe means (not shown) adapted to mark drum 20. Thus a complete pressurediagram may beobtained in a;step-bystep manner.

The improved unit l6 shown in detail in Figs.

2 and 3 comprises a body 2 5 having external threads 25 by which it maybe secured in the cylinder head I4, a lower end having a transverse wallor flange 26 through which port 2'! opens to the interior of the body,and an upper and enlarged end having internal threads 28 at the openend. zone of the body bore 29. The lower flanged end 26 of the bodyforms an internal annular seat 30 for receiving a diaphragm block 3!upon a seat gasket 32. The diaphragm element 33 is positioned on theupper recessed surface of block 3! and a second block 34 is positionedthereover to define a restricted chamber 35 within which the diaphragmis confined with a suiiicient working clearance so as to permit freebodily movement to a limited extent in the axial direction of the body24. A holder element 36 for an electrode 7 34. Apertures 38 may belocated in a circular pattern concentric with the axis of the unit andoutwardly of an undercut central recess 4! in the liglder for thereception of an insulator element The electrode 31 is formed with anupper threaded stem 43, a mounting flange Ml and a lower tip 45 ofreduced diameter. Flange 4 is positionable in the recess M of the holder36 and is spaced therefrom by the insulator 42 upon positionment of thelatter over the stem 43 and against the upper surface of the flange 44.Electrode 31 is clamped to the holder by means of the nut 49 threaded onstem 43 and bearing against a washer 46 and an insulatin washer 47, thelatter being seated against the holder 35. The upper portion of thethreaded stem 43 of electrode 31 engages the threaded socket element 48of the elongate rod 59. The socket element 48 is formed of an electricalconductive material, and constitutes the circuit connection between theelectrode 31 and the rod 50. Rod 5i! (Fig.2) extends toward the upperopen end of the body 24 and carries an electrical connector element 5|which is press-fitted thereover by means of the socket portion 52 suchthat the integrally formed connector post 53 thereof is positionedwithinthezone of the threads 28 in the body 24.

The parts of the assembly above described are secured in the body 24 bymeans of the body cap, member 55 (Fig. 2) wherein the threaded portion56 thereof engages in the body threads 28 and serves to press a spacersleeve 57 positioned in the bore 29 against the electrode holder 36 and,hence, compress the diaphragm blocks 3! and 34 against the sealinggasket 32 upon seat 39 at the lower end 26 of the body 26. Suitablegasket elements 58 and 59 are interposed at opposite ends of the sleeve,5! as shown. The portion 56 of the cap member 55 is internally recessedto provide a seat 60 for the insulator block 6| which maintains theconnector element post 53 in axially concentric position relative to thebore 29 of the body 24. This latter block 6! is formed with a suitablenumber of radial notches 62 (only one being shown in Fig. 2) whichpermit communication between the space 39 within sleeve 51 and a pocket63 provided above the Cap member 55 is also formed with an enlargedportion (i i in the nature of a tool engaging nut for effecting threadedpositionment thereof in body 24, and a stem portion 65 extending abovethe boss 64 to provide a mounting surface for the slip ring element 65.The slip ring is held in position by the nut 67 threaded on stem 55, andis fully insulated therefrom by means of the sleeved insulator 68 andthe an nular insulator 6t. Nut 61 bears on washer iii to protect theinsulator 59 from damage by the rotation of the nut. An electrical leadH extends from its soldered connection at post 53 through suitableapertures in the boss 64 and insulator to a soldered connection in theslip ring 65, all as indicated in Fig. 2. The ring E6 is suitably formedof an electrically conductive material, such as copper.

Connection of the pressure line 19 to the unit it is efiected by meansof the threaded fitting l2 engaging the upper end of the stem 65 abovenut 6! so that the line l9 opens to the axial bore 13 of the member 55for communication with the pocket 63 and thence through notches 62 inthe insulator block 6| to the space 39. At the lower end of the body 24,the space 39 communicates with the upper face of the diaphragm 33 by Wayof the annular space around the insulator 51, the annular ring ofapertures 38 in the holder 36, recess id of the upper diaphragm block 34and the several axially directed apertures formed in the latter block.The electrical circuit for this indicator it includes the body 24 andblock 35 on one side of the diaphragm 33, and the electrode 3?, socket8, rod 59, connector 5i, lead ll,

slip ring 6 5 and external lead wire it for the to provide an axiallydirected, peripheral rim Tl.

extended above the general facial plane thereof, and this plane isfurther milled out to form a series of annular and concentric notchesorgrooves i3 separated by similar lands 19 of a co-planar character.Thus the diaphragm 33 is adapted to be supported on the lands 79 with asmall Working clearance at the rim 71. In a similar manner, the upperblock 34 is provided with a plurality of axially directed apertures 8|leading from the recess 43 to the diaphragm The lower face of this block34 ischamber 35. formed with a series of annular notches or grooves 82and intervening lands 83 which are in oppositely registering alignmentwith but spaced from the lands l9 on the lower block 3!. The spacing ofthe two blocks SI and as is determined by the rim ll. Electrode element3'! is positioned, in assembly, with its tip 45 extending into thecentral one of the apertures 8i with small clearance and such that itsdiaphragm' contact face 84 is substantially flush with thecommon planeof the lands 83.

In a pressure responsive unit of this character the diaphragm chamber 35defined by the blocks 3! and 34, is open through apertures 16 and port2? to the source of pressure to be investigated,

and through apertures BI and recess 4% to the source of pressure undercontrol of the instru-' ment i? as supplied through line I9 at fittingl2. Diaphragm 33 effectively divides this chamber 35 into sections, andeffectively prevents cross flow by its seating contact on either one orthe.

other series of land surfaces depending upon which source of pressure isdominant. A pre-.

ametes ferred construction; and "one which has provedentirely-satisfactory, embodiesa diaphragm element 33 having a thicknessof substantiallyefll-fl inch workingin chamber. .35 .having an axialdepth of substantially .011 inch; Thus the diaphrag'm is movable througha distance off ;001 inch from its'contact --on-b1o'ck -'3 to its contactwith ditch s! and electrode tip iace 84 In this sameembodiment,the-diaphragm was formed of Beryllium bronze for its strengthand durability under the high pressure and temperature conditionsencountered in internal combustion engine use.

The light weight and tough character of the diaphragm renders itextremely sensitive to pressure variations occuring in the differentsections of the chamber 35. A further feature hereof resides in theprovision of a minimum amount of movement for the diaphragm, therebypractically eliminating inertia effects and consequent time lag for theelectrical make or break action on the tip face 84 of the electrode 31.Moreover, the free mounting of the diaphragm entirely eliminates theintroduction of errors due to fatigue of the diaphragm, such as isencountered in the prior units where the diaphragm is peripherallyclamped in situ.

Having now fully described my improved pressure responsive unit I6, itwill be understood that I do not wish to be limited to the exactfeatures of its construction but intend that all reasonable variantsthereof be included within the spirit and scope Of the appended claims.

I claim:

1. A pressure responsive unit comprising a body having relatively spacedopenings for communication with a periodically pressurized space and asource of known pressure respectively, an electrode element positionedin said body, 21 diaphragm element operatively mounted in said bodyadjacent said electrode element, said diaphragm element being freely andbodily movable toward or away from said electrode element under theinfluence of the differential of pressures from said space and knownpressure source, and means in said body for confining said diaphragm tolimited movement, said means :providing openings at each side of thediaphragm for pressure transmission thereto and said openings beinglocated so as to be closed by diaphragm whereby to preventcross-communication of the space and pressure source.

2. A pressure responsive unit comprising a body having relatively spacedopenings, one of which is adapted to communicate with a periodicallypressurized space and the other with a source of known pressure, anelectrode element positioned in said body and electrically insulatedtherefrom, and a diaphragm element operatively mounted in said bodyadjacent said electrode element and in position effectively to preventcross flow between the pressurized space and known pressure source, saiddiaphragm element being freely, bodily movable toward or away from saidelectrode element under the differential pressure effects from saidknown pressure source and pressurized space.

3. A pressure responsive unit comprising a body having relatively spacedopenings for communication with a pressurized space and a source ofknown pressure respectively, a pair of elements in said body formed todefine a chamber therebetween, said elements each having an aperturetherein to permit communication between said chamber and the pressurizedspace and known 6 sourceol pressure,sand a' diaphragm''freeiyinmvablydisposed in said chamber-4m efie'ctingcios ure"oftne'-'aperturesineither of said elements" 'under th'e" in'iluen'ce -of a pressuredifferential across-the diaphragm.

4. pressure responsive unit comprising a bod-"y having an"inwardl-y'flanged end providing aport and an annular seat adjacentthereto, n: block element on said seat and having apertures thereinand-a: recess in one face communicating:-

with saidiport through the aperturespa second block element positionedadjacent the recess "in said first block to deflne a recess chambertherewith, said second block having apertures formed therein, adiaphragm in the recess chamber between said block elements, saiddiaphragm being freely, bodily movable against either of said blockelements to close the apertures therein, and means for communicating aknown source of pressure through said second block element and againstone face of said diaphragm, said port in the flanged end of said bodybeing adapted for communicating a source of pressure to be investigatedthrough said first mentioned block element and against the oppositefaces of said diaphragm.

5. In a pressure responsive unit, an elongate body having a bore thereinand a ported flange formed at one end thereof, the flange defining aninternal annular seat in said body, an apertured block positionedagainst said annular seat and having a recess formed in one face toprovide a peripheral rim directed axially of the body bore, a secondapertured block positioned against the peripheral rim of said firstblock to define a chamber with the recess of the latter block, adiaphragm element freely, bodily movable in said chamber and adapted tocontact either of said blocks in aperture closing relation, and anelectrode element carried in the body bore and formed with a tip portionextended through an aperture in said second block for contact by saiddiaphragm upon movement of the latter into contact with said secondblock, said diaphragm being movable in response to the difference ofpressure on its opposite sides due to disposition of said body betweenseparate sources of pressure.

6. In a pressure responsive unit, a body having an axial bore and aported flange at one end of the bore to define an internal annular seat,a body cap member engageable at the opposite end of the body bore, andhaving a passage communicating with said bore, a pair of complementaryblock elements in said bore formed with a plurality of axially directedapertures and defining a. chamber between their adjacent faces, meansfor securing said block elements against said annular seat upon assemblyof said cap member, a diaphragm element disposed in said chamber forfree bodily movement between said block elements, an electrode elementprojecting into an aperture of one block element for contact by saiddiaphragm upon movement thereof against said one block, electricalconnection means carried by said cap member, means for electricallyassociating said connection means and said electrode element, and meanson said cap member adapted to connect the body bore with a source ofpressure such that said said diaphragm is urged to a position out ofcontact with said electrode and in opposition to a source of pressurecommunicated to said chamber at the opposite side of the diaphragmthrough said ported flange.

'7. A pressure responsive unit comprising a body having relativelyspaced openings and a bore communicating said openings, the body 7openings being adapted for communication re- REFERENCES CITED spectivelywith pressurized Space and June The following references are of recordin the of known pressure, means in said bore defining me of this patent;

a chamber having apertures respectively afford- I ing communication ofthe chamber with the 5 UNITED STATES PATENTS pressurized space and knownsource of pressure, Number Name Date and a diaphragm element freely,movably dis- 2,072,984 Haskins Mar. 9, 1937 posed in the chamber andacting selectively and 2,085,203 Schlesman et a1. June 29, 1987 underthe influence of difierential pressures to 2,362,874 Wiley Nov. 11, 1944close certain of said apertures to prevent cross-' 10 communication ofthe pressurized space and known pressure source.

KENNETH L. MCGUIRE.

